$include instead of $import for run:?

Is it possible to use $include for the value of ‘run:’ in a workflow step? (just curious as $import does work) If so how can it be done? When I use $include I see these errors:

=> cwltool --debug --validate cwl_tool_wrapper_workflow.cwl 
INFO /Users/waltershands/.pyenv/versions/3.9.6/bin/cwltool 3.1.20211020155521
INFO Resolved 'cwl_tool_wrapper_workflow.cwl' to 'file://.../cwl-tool-wrapper-workflow/cwl_tool_wrapper_workflow.cwl'
ERROR Tool definition failed validation:
cwl_tool_wrapper_workflow.cwl:17:1: checking field `steps`
cwl_tool_wrapper_workflow.cwl:18:3:   checking object
cwl_tool_wrapper_workflow.cwl:25:5:     Unsupported scheme '' in url: #!/usr/bin/env cwl-runner

The difference between $import and $include is that $import loads it as a structured document and $include is just the file contents as a string.